1. Field of the Invention
This invention relates to a manipulator for inspecting and, if required, repairing the tubes of heat exchangers, especially of steam generators for nuclear reactors, where the steam generators comprise at least one tube bundle which is set in a tube sheet and leads into a steam generator chamber, and the manipulator is brought through a lead-in nozzle of the steam generator housing with an inspection arm and can be aligned with a mouthpiece arranged at the free end of the inspection arm onto individual tube openings of the steam generator tube sheet and can be brought into engagement with these tube openings in such a manner that inspection instruments and/or tools such as eddy current probes, cleaning plugs, explosive plugs or the like can be introduced into the steam generator tubes through the mouthpiece under remote control.
2.Description of the Prior Art
A manipulator of this type is described in German Pat. No. 2,316,074 and U.S. Pat. No. 3,954,136. The inspection arm shown in the patents is bent off at its outer end and can be run into a rest position in a niche of the primary steam generator chamber, so that the flow is not impeded or only slightly impeded. With this known manipulator, it is not possible, however, to remove the inspection arm from the steam generator chamber after the inspection is completed. In addition, the tube field that can be reached by the known inspection arm, is limited. These are the difficulties to be overcome by the invention. From British Pat. No. 1,207,790, it is known in connection with a remotely controlled closing device, especially a tube plug-up device, for heat exchangers of nuclear installations, to introduce an arm carrying a closing device through a nozzle of the heat exchanger into a heat exchanger chamber and also to remove it after the heat exchanger tubes have been plugged up, where evidently a plate serving as a template during the repair is replaced by a cover plate. The plugging-up device here has a relatively large dimension in the direction of the tube sheet plane, so that the lead-in nozzle must have a relatively large diameter; on the other hand, the tube sheet in this heat exchanger is relatively small so that there is no problem for the plugging-up device to reach all heat exchanger tubes. The present invention, on the other hand, is addressed to the problem of not letting the inside diameter of the inspection nozzle become too large, and providing an inspection device that can be inserted into the steam generator chamber through the relatively small inspection nozzle so that all or practically all openings of the heat exchanger tubes can be reached by it under remote control.